A known prior art packaging bag for beverages such as juice, coffee, and soybean milk, is provided with means for facilitating piercing a straw into the packaging bag, which means consists of embossments only formed on the outside of the bag. Piercing of a straw through the embossments may be easily done when the bag panels are relatively thin. However, the panel thickness is commonly made thicker in order to maintain the quality of the contents for a longer period, and to more effectively prevent rupture of the bag. Easy piercing by an ordinary straw is not possible with such a thick-panelled packaging bag, particularly when the laminar panels of the bag comprise a combination of polyester film, biaxially stretched polypropylene film, nylon film, cellophane, or aluminum foil.
A typical prior art beverage packaging bag is taught in Orsini U.S. Pat. No. 3,006,257. The Orsini Patent teaches a method of making a bag of a thermo-weldable material but is not concerned with making a bag that can be readily pierced by a straw. Parks U.S. Pat. No. 3,524,566 is concerned with a rigid lid for a disposable drinking cup, the lid having a weakened area for insertion of a straw. Centrally located on the lid is a domed portion having a score around the top thereby forming a weakened area which can be pushed in by a straw. This, however, is quite different from a bag or flexible pouch which can be pierced by a straw. The lid is rigid while the bag with which the present invention is concerned is flexible. The lid is placed on a drinking cup after the cup is filled and is used immediately thereafter. Thus, it is not necessary to make it in such a way that it can withstand normal handling during automatic packaging operations, shipping to a point of sale, and being handled by the consumer.
Kramer et al. U.S. Pat. No. 4,072,233 is concerned with a flexible container having a frangible piercing point. The frangible, or weakened, area is made by cutting, stamping, or the like to form a depression part way through the wall of the bag, the wall commonly being a multi-layered laminate. The disadvantage of forming the weakened area by mechanical means is that the depth of the weakened area cannot be accurately controlled and a weakening beyond the desired depth often occurs.